1. Field of the Invention
The present invention relates to a solid-state imaging device including lenses provided above a semiconductor substrate on which light receiving portions such as photoelectric conversion portions are formed, the lenses guiding incident light to the light receiving portions.
2. Description of the Prior Art
Generally, a solid-state imaging device such as a MOS image sensor is structured such that over a semiconductor substrate having a light receiving portion (a photoelectric conversion portion such as a photodiode), a variety of films such as a light-shielding pattern and an interconnect pattern is disposed in multi-layered manner. When such a solid-state imaging device is downsized, the exit pupil distance of a camera lens necessarily shortens. This increases an oblique component of light entering a pixel array portion (imaging area), especially the periphery of the pixel array portion, wherein in the pixel array portion, a plurality of pixels are two-dimensionally arranged. Therefore, when it comes to each pixel, as the incident angle of light increases, a component of the light blocked by interconnects or the like is large and the quantity of light directly entering a light receiving surface decreases. Therefore, it becomes difficult to keep image quality at a high level.
Japanese Published Unexamined Patent Application No. 2000-124434 discloses a conventional technique in which a light collection lens (inner-layer lens) is formed in an upper level film of an image sensor to improve the light receiving sensitivity, wherein the light collection lens is formed by a high refractive index material such as a P—SiN film (a silicon nitride film formed by plasma CVD), and an upper face of the light collection lens is formed as a convex lens face.
Moreover, Japanese Published Unexamined Patent Application No. H02-309674 discloses a solid-state imaging device as shown in FIG. 16 including: a light receiving element 112 provided on a surface portion of a substrate 111; and a light collection lens 116 disposed above the substrate 111, wherein a focal point of the light collection lens 116 is situated below an upper face of the substrate 111 to improve the sensitivity.